Erend seemed to shake all the Elves in this depressive building. No, actually Erend has shaken up everybody here including his three human companions.
Erend had just challenged an Elf Prince. Which is basically the being that has the most power in this place. He was also probably the strongest among all the Elves here.
But Erend showed that he wasn't someone who could be affected by that status.
Erend is like saying: 'To hell with you and your whole position as a prince. If you mess with me, I will go rampage on your precious city.'
Although basically, even Erend himself wasn't sure that he could beat Aerchon.
But after hearing Aerchon's words which were completely unreasonable and only based on his hatred for them, Erend couldn't just sit back and accept everything like Billy, Elis, and Lt. Boartusk.
Erend wouldn't blame them. They knew how powerful the Elves were and trying to challenge them without preparation would only be suicide. But Erend was different from them.